Added externs declarations to header files to handle C++ compilation.

Cleaned up BACnet/IP API a little.

bacnet-stack/rs485.h

@@ -39,6 +39,10 @@
 #include <stdint.h>
 #include "mstp.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
 void RS485_Initialize(void);
 
 void RS485_Send_Frame(
@@ -51,4 +55,8 @@ void RS485_Check_UART_Data(
 
 void RS485_Process_Tx_Message(void);
 
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
 #endif